1. Field of Invention
The invention generally relates to remote sessions, and, more particularly, to generating a graphical display for a remote terminal session.
2. Description of Prior Art
A thin-client protocol is used for displaying output, produced by an application running on a server, on a client with limited processing capabilities. Two exemplary thin client protocols are ICA, Independent Computing Architecture from Citrix Systems, Inc., Ft. Lauderdale, Fla. and RDP, Remote Desktop Protocol from Microsoft, Inc., Redmond, Wash. The client is also sometimes referred to as a remote terminal session. One thin-client protocol intercepts commands by the application program to the server operating system (“OS”) to draw to a display screen. The intercepted or similar commands are transmitted to the remote session, using for example, the presentation layer packet. When the remote session (e.g., thin-client) receives the command, the remote session passes the received commands to the remote session OS. The thin-client draws the application program output on its display using the received commands as if the application program were executing on the thin-client.
Typically, when the application program draws images to the display screen, the image is represented as a bitmap. A bitmap format of an image is generally a very large data set. Thus the thin-client protocol must transmit over the network the bitmap representation of an image, which is a large amount of data, along with the applicable commands on how to display the bitmap representation. For networks of low bandwidth, this results in a large time delay before the complete image is received and displayed on the client. This can result in inconvenience and unhappiness for the user of the client. Also, if the user is paying directly for bandwidth used, for example in a wireless network, transmission of these large bitmap formats results in large costs associated with each transmission.